Direct action magnetic shutter



Feb. 22, 1955 A. 6. DE BELL DIRECT ACTION MAGNETIC SHUTTER INVENTOR.ARTHUR G. DEB ELL Filed March 20; 1952 ATTORNEYS United States PatentDIRECT ACTION MAGNETIC SHUTTER Arthur G. De Bell, China Lake, Inyokern,Calif.

Application March 20, 1952, Serial No. 277,709

1 Claim. (Cl. 95-58) (Granted under Title 35, U. S. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

The present invention relates to a magnetic shutter and moreparticularly to a magnetic shutter that is directly actuated by amagnetic field.

Previously used shutters are actuated by means of a solenoid acting onan armature which in turn acts on the shutter blades through gearlinkages and other mechanical movements. The disadvantages of thesemethods employing mechanical linkages are:

(l) Uncertainties in the exact acting time of the shutter due tomechanical play and lag;

(2) Uncertainties in the duration of the shutter opening due to play,lag and friction in mechanical movement;

(3) Relative slowness in action due to inertia of heavy moving parts.

The disadvantages encountered in prior art shutters are overcome by thepresent invention in which the butterfly vanes of the shutter are madeto move as desired by the application of a magnetic field. The vanes aremounted on pivots and pivot bearings and are free to turn as soon asthey are acted upon by the magnetic field. Since the vanes have nomechanical linkages the shutter will act, by either opening or closing,at a definitely determined time so as to admit light to a photographic,optical, or similar system, during a precisely controlled interval oftime.

An object of the present invention is to devise a magnetic shutter thatwill accurately operate at a specifically desired moment.

Another object of the present invention is to devise a magnetic shutterthat will operate for a precisely determined interval of time.

A further object is to devise a magnetic shutter that has a rapidresponse.

A still further object of the present invention is to provide a magneticshutter that can be operated in whatever sequence of exposures isdesired.

A final object of the present invention is to provide a magnetic shutterthat may be quickly regulated by simple adjustments to its electricalcircuit.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein: 1

Fig. 1 illustrates a plan view of a preferred embodiment of the presentinvention in the closed position.

Fig. 2 is a front elevation of the present invention in the closedposition.

Fig. 3 is a plan view of the present invention in the open position.

Fig. 4 illustrates a front elevation of the present invention in theopen position.

Referring now to the drawing wherein like reference characters designatelike or corresponding parts throughout the several views, there is shownin Fig. 1 through Fig. 4, a plurality of high permeability,ferromagnetic, butterfly vanes, 16, to alternatively obstruct light orallow it to pass, are actuated by means of a set of hollow shutteropening coils, 13, and 14, energized by a controlled electrical powersupply, 25, which produces a magnetic field,

22, that is approximately parallel to the direction of light through theshutter, as illustrated by arrow 26; and a set of closing coils, 11, and12, energized by a controlled electrical power supply 24, which producesa magnetic field, 21, that is essentially at right angles to thedirection of light travel, as illustrated by arrow, 26, through theshutter. The vanes are supported by a rectangular metal frame, 19,provided with a non-conducting insert, 20, which forms an integral partof the frame so as to break the continuity of the metal frame structurethereby preventing said frame from acting as a short-circuited turnlinked to the magnetic field, 22, produced by the opening coils, 13, and14. The coils are internally dimensioned to match the external size ofthe frame so that when the shutter-opening coils are energized the frameand its contained vanes will be engulfed in the resulting flux stream. Aframe constructed of non-conducting material may be used in place of themetal frame, in which case the non-conducting insert would beunnecessary. Pivots, 17, are secured to both ends of each vane, and areset in jeweled V-bearings, 18, which are non-conducting and have a lowcoefiicient of friction. Stop pins, 15, secured to frame, 19, define theclosed position of the vanes, while stop pins, 23, define the openposition of the vanes, both of which thereby permit approximatelyoscillation of the vanes. As is shown in Fig. 1, close stop pins, 15,are located in a line parallel to the direction of magnetic field, 21,and on centers with the pivots, 17, so as to place the vanes, 16, at aslight angle to the direction of the magnetic field, 21. Fig. 3,illustrates the location of open stop pins, 23, located with respect toeach of the pivots, 17, in lines which are substantially parallel to themagnetic field, 22, thereby placing the vanes parallel to the directionof magnetic field, 22.

As alternatives to the use of the above described coils, an arrangementof permanent magnets may be set up to control the shutter; or by the useof core material of higher permeability than air, the coils may beplaced in more convenient location.

As alternatives to the vane assembly, permanent magnets may be used asvanes thereby resulting in a reaction between their own magnetic fieldsand the magnetic fields provided by the coils or other external fields;or the vanes may be made of non-magnetic material with small permanentor induced magnets directly secured to them, or their pivots.

With the foregoing in mind and referring to Figs. 1 through Fig. 4, theoperation of the device is as follows:

When the closing coils, 11, and 12, are energized to produce a magneticfield, 21, parallel to the axes of these coils, the vanes, 16, are linedup approximately parallel to the magnetic field, and approximatelynormal to the direction of light, 26, and are limited to this positionby closed stop pins, 15. During this period when the vanes areobstructing the light, the shutter is considered closed, during whichtime the opening coils, 13, and 14, are not energized. At the end of theclosed period, the current in the closing coils is diminished frommaximum to zero value thereby diminishing the magnetic field, 21,produced by this current; at the same time the current in the openingcoils, 13, and 14, is increased from zero to maximum value therebyincreasing the magnetic field, 22, produced by this current. Theincrease in magnetic field, 22, parallel to coils, 13, and 14, and thedecrease in magnetic field, 21, parallel to, 11, and 12, produce ineffect a rotating magnetic field, which the magnetic axis of the vanesas seen in Fig. 1 and Fig. 3, tend to follow. The vanes rotate to theiropen position as defined by open stop pins, 23. The current in theopening coils, and the attendant magnetic field, 22, remain on duringthe open period. There is no current in the closing coils.

At the end of the open period the current in the opening coils isdiminished from maximum to zero value while the current in the closingcoils is increased from zero to its maximum value. These changes incurrent produce a rotating magnetic field which causes the vanes torotate to the closed position where they set against close stop pins,15. The shutter is now closed and the cycle may be repeated at will.

The open stop pins, 23, may be located on-center with the axis of pivot17, thereby positioning the vanes, 16, at a slight angle to the magneticfield, 22. In such case the magnetic fields need not be synchronized toproduce a rotating field; instead one of the fields may be utilized torotate the vane without the aid of the other.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

Having thus described the invention what is claimed is:

A photographic shutter consisting of a centrally open non-magneticframe, a set of hollow shutter-opening coils in axial alignment with thedirection of light travel, said coils comprising serially connectedcomponents in confronting relationship to opposite open sides of theframe and being internally dimensioned to substantially match theexternal size of the frame thereby to engulf the frame in the fluxstream When the coils are energized, a set of shutter-closing coilsaxially oriented at a right angle to the shutter-opening coils andcomprising serially connected components confronting opposite ends ofthe frame, and a plurality of flat vanes made of magnetic materialpivotally mounted in said frame to assume face-on relationship to theopening coils when the closing coils are energized and to assume edge-onrelationship to the opening coils when said opening coils are energized,the pivot axes of said vanes being located in a common plane and normalto the axes of the opening and closing coils, said pivot axes being inthe center of said vanes and parallel to each other and equally spaced,the distance between said axes being less than the Width of one vane.

References Cited in the file of this patent UNITED STATES PATENTS562,599 Friese June 23, 1896 660,006 Doyen Oct. 16, 1900 1,913,182Williamson June 6, 1933 1,919,115 Maury et al. July 18, 1933 1,934,519Anderson Nov. 7, 1933 1,983,898 Cole Dec. 11, 1934 2,105,475 DraegerJan. 18, 1938 2,390,216 Guedon Dec. 4, 1945 2,528,510 Goldmark Nov. 7,1950 2,572,229 Willcox Oct. 23, 1951

